JP2009127682A - Air spring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air spring having a resin made piston hardly broken even during unwonted air leakage while securing large volume in a diaphragm interior and the piston, and being lightweight and inexpensive, in an air spring using a resin made piston. <P>SOLUTION: The air spring includes a connection plate 18 mounted to an upper side member, the piston 20 mounted to a lower side member, and a diaphragm 21 connected to respective one ends of the connection plate 18 and the piston 20. An expansion and contraction chamber 36 formed in the diaphragm 21 interior is communicated with an air chamber 37 formed in an interior of the piston 20. The piston 2 is joined to a resin made piston body 23 and a lid member 24. Ribs 31 are radially provided in an interior of the piston body 23, an inner face of the lid member 24 is fit on tips of the ribs 31, and buckling and overturning of the ribs 31 are prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an air spring used for a suspension device such as a large vehicle or a construction machine.

  In large vehicles such as trucks, buses, and railway vehicles, a suspension system or suspension is attached between the axle provided with the traveling wheels and the vehicle body in order to mitigate vibration and impact propagation from the axle side to the vehicle body side. In a construction machine, a suspension device is attached between a cab and a body frame. A suspension device for a large vehicle has a suspension spring and a shock absorber attached to the suspension spring, and a laminated leaf spring, a coil spring, an air spring, or the like is used as the suspension spring.

  The air spring used in the suspension system is designed to keep the vehicle height constant even when the load of cargo or the like changes, by adjusting the length dimension by supplying and discharging compressed air from the outside to the inside expansion and contraction chamber. As well as being able to hold, since the elasticity of air is used, the spring constant can be set lower than that of a leaf spring or a coil spring, and the ride comfort can be improved. .

  There are two types of air springs: bellows type and diaphragm type. The diaphragm type air spring is attached to a rubber diaphragm (cylindrical elastic membrane) with a metal reinforcing cord inside and attached to the lower end of the diaphragm. The diaphragm is attached to the vehicle body side of the large vehicle, and the piston is attached to the axle side.

In recent years, hollow pistons used in air springs have been molded from resin materials such as synthetic resins in order to reduce weight and cost. The resin-made piston has a cylindrical portion and an end wall portion integrally provided at one end portion thereof, and Patent Literature 1 describes an air spring having a piston with the end wall portion as an upper side. 2 shows an air spring having a cylindrical portion with an inner and outer double structure.
JP 2006-112500 A JP 2004-316785 A

  In the air spring in which the end wall portion of the cylindrical portion is provided on the upper side, the hollow chamber of the piston opens to the outside, and the expansion / contraction chamber inside the diaphragm is partitioned by the end wall portion of the piston. When the inner and outer air chambers are made to communicate with the expansion and contraction chamber, the capacity of the expansion and contraction chamber inside the diaphragm including the air chamber in the hollow portion of the piston can be increased. The spring constant can be reduced without increasing the overall length of the spring.

  As described above, the piston having the inner and outer double structure of the cylindrical portion has an outer main body cylindrical portion and an inner bottomed cylindrical portion integrated with an annular upper side wall portion. The space is communicated with the space in the bottomed cylinder part through a communication hole, and a lid member is attached to the lower end of the piston via an O-ring in order to airtightly close the opening of the bottomed cylinder part. . When a lid member is brought into close contact with the lower end of the piston through an O-ring and combined with each other by a single connecting bolt, a shocking large load is applied to the air spring. When a spring is used for a large truck, and over a large road surface convex part in the loaded state, the internal pressure of the internal expansion / contraction chamber or air chamber suddenly rises and the main body cylinder part is in close contact Compressed air may leak to the outside from between the cover member and the lid member.

  As described above, when the lid member is attached to the lower end portion of the main body cylinder portion, since these connection portions are arranged on the lower side, the connection portions are always exposed to the outside, and the connection portions are exposed to wind and rain. There is a possibility that the O-ring may be prematurely deteriorated by being exposed or having dust or the like in the connection portion. Moreover, since it is necessary to shape | mold the main body cylinder part and a cover member with high intensity | strength so that it can endure the load added repeatedly over a long period of time, the manufacturing cost of a piston will increase. Furthermore, in order to manufacture the piston, it is necessary to mold the main body cylinder part and the bottomed cylinder part integrally with resin, and after performing die cutting, drill the hole in the bottomed cylinder part as a post process. The manufacturing process was complicated.

  An object of the present invention is an air spring using a resin piston, which is a resin piston that is light and low in cost while ensuring a large volume in the diaphragm and in the piston, and is hardly destroyed even in the event of an air leak. It is providing the air spring which has.

  An air spring according to the present invention is an air spring that is mounted between an upper member and a lower member disposed below the upper member, and relieves vibrations propagated from the lower member to the upper member. A resin-made piston main body having a closed wall provided with a boss portion attached to one of the upper member and the lower member, and a cylindrical wall extending in the axial direction from the closed wall, and having an open end at the tip A resin lid member that forms a piston that is joined to the opening end of the piston body and has an air chamber therein, and a connection that is attached to the other of the upper member and the lower member One end is fixed to the plate, while the other end is fixed to the mounting cylinder through a folded portion that covers the outside of the cylinder wall, and forms an expansion / contraction chamber that communicates with the air chamber inside Each of the closures A plurality of ribs extending in the axial direction from the cylindrical wall toward the lid member and radially extending from the cylindrical wall toward the boss portion are integrally formed radially on the piston body, and the ribs are formed on the inner surface of the lid member. A fitting portion is formed to be fitted to the end portion.

  The air spring of the present invention is characterized in that a reinforcing protrusion extending in the axial direction is provided on the rib, and the reinforcing protrusion is provided on the radially inner side of the rib.

  The air spring of the present invention is characterized in that the reinforcing protrusion is provided in correspondence with the mounting cylinder portion, and the fitting portion to be joined to the axial end portion of the reinforcing protrusion is provided in the lid member. And

  The air spring of the present invention is characterized in that the fitting portion is provided on the inner surface of the lid member so as to protrude into the piston body, and the fitting portion and the end of the rib are joined by welding. Features.

  According to the present invention, the resin-made piston is formed by the lid member having the mounting cylinder part and the flange part, and the piston main body having the blocking wall and the cylinder wall, so that the weight of the piston can be reduced. In the piston body, the closing wall and the cylindrical wall are integrated, the rigidity of the piston can be increased, and the leakage of compressed air from the air chamber to the outside can be reliably suppressed. Also, in the piston molding process, the air chamber is formed inside the piston body by removing the die from the opening end side of the piston body, so that a post-process for forming the air chamber becomes unnecessary, and the piston manufacturing process It can be simplified.

  According to the present invention, the joint portion between the piston body and the lid member is covered with the folded portion of the cylindrical elastic membrane, so that the joint portion can be prevented from being exposed to the outside. Therefore, the joint portion is protected by the folded portion of the cylindrical elastic film, and deterioration at the joint portion can be suppressed.

  According to the present invention, ribs are provided radially in the piston body, and the ribs are fitted to the fitting portions provided on the inner surface of the lid member. And the rigidity of the piston consisting of the lid member joined to this can be increased.

  According to the present invention, since the piston main body and the lid member are integrated by welding the respective abutting portions, the bonding strength between the piston and the lid member can be improved.

  According to the present invention, the ribs are provided with reinforcing protrusions to increase the strength of the ribs, so that the ribs can be prevented from buckling or falling. By providing the reinforcing projection at a position corresponding to the mounting cylinder, even if an excessive load is applied to the mounting cylinder, there is a rib with a reinforcing projection directly below, so that buckling and overturning of the rib can be prevented, The strength of the piston can be increased. By providing the fitting portion so as to protrude from the inner surface of the lid member, the strength of the lid member is not impaired.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing an air spring suspension mounted on a truck. FIG. 1 shows one of the left and right sides of the rear end of the body frame of the truck. The body frame 10 is provided with two axles 12 with traveling wheels 11 mounted on the left and right ends, respectively. An air spring suspension 13 is mounted between each axle 12 and the vehicle body frame 10 in order to mitigate vibrations and shocks from the road surface transmitted from the axle 12 to the vehicle body frame 10.

  The air spring suspension 13 includes a link mechanism 14 having a bracket 14a fixed to the vehicle body frame 10 and an arm member 14b rotatably connected to the bracket 14a at a base end portion. Two air springs 16 and a shock absorber 17 are mounted between the support member 15 connected to the tip and the vehicle body frame 10, and the air spring 16 and the shock absorber 17 are supported by the vertical movement of the traveling wheel 11. It is designed to expand and contract in accordance with 15 vertical movements.

  2 is a sectional view of an air spring according to an embodiment of the present invention, FIG. 3 is a perspective view showing a piston body of the air spring, and FIG. 4 shows an inner surface of a lid member fixed to the piston body. It is a perspective view.

  The air spring 16 is a diaphragm type air spring, and is attached to a metal connecting plate 18 attached to the vehicle body frame 10 as an upper member and a support member 15 as a lower member, as shown in FIG. It has a synthetic resin piston 20 and a rubber diaphragm 21 as a cylindrical elastic membrane provided between them.

  The connecting plate 18 is formed by punching a metal plate such as a steel plate into a substantially disk shape by pressing or the like, and a bracket 22 is attached to the center of the outer surface by welding means such as arc welding. The bracket 22 of the connecting plate 18 is attached to the vehicle body frame 10 via a fastener such as a bolt (not shown). On the outer peripheral portion of the connecting plate 18, a curled portion 18 a formed by bending downward toward the piston 20 in FIG. 2 is provided. The curled portion 18 a is fixed to one end portion of the diaphragm 21 so as to sandwich the curled portion 18 a so that the airtightness inside the diaphragm 21 is maintained. A metal wire 19 a is embedded in one end portion of the diaphragm 21. ing.

  The piston 20 has a piston main body 23 and a lid member 24 joined to the piston main body 23, and each is formed of a resin material. The piston main body 23 extends in the axial direction from the outer peripheral portion of the blocking wall 26 to the lid member 24, with a blocking wall 26 provided with a boss portion 25 attached to the axle 12 via a support member 15 that is a lower member. A cylindrical wall 27 is provided, and the upper end is an open end 28. The boss portion 25 protrudes from the central portion in the radial direction of the blocking wall 26 to the inside of the piston main body 23, and the protruding length is about one half of the axial length of the piston main body 23. The boss portion 25 is provided with a metal nut member 30 in which a screw hole 29 is formed. The nut member 30 is integrally incorporated in the piston body 23 when the piston body 23 is molded. A plurality of annular protrusions are provided on the outer periphery of the nut member 30 so that the boss portion 25 and the nut member 30 are firmly fixed, and the piston 20 is attached by bolts (not shown) that are screwed to the nut member 30. The piston body 23 is attached to the support member 15 at the portion.

  As shown in FIGS. 2 and 3, the piston body 23 has ribs extending in the axial direction from the closed wall 26 toward the opening end 28 and radially extending from the cylindrical wall 27 toward the boss 25. Twelve 31 are provided at equal intervals in the circumferential direction, and the strength of the piston body 23 is enhanced by these ribs 31. In the piston main body 23, the boss portion 25 and the cylindrical wall 27 are partitioned into small spaces by radial ribs 31, and each small space is interposed through a space between the front end surface of the boss portion 25 and the opening end 28. They communicate with each other.

  The lid member 24 has a circular flange portion 33 and a mounting tube portion 34 extending outward in the axial direction from the inner peripheral portion. An annular edge protruding from the bottom surface of the flange 33 is provided on the outer periphery of the flange 33, and the end surface of the edge is abutted against the abutment surface 32 on the opening end 28 side of the piston body 23. Surface 35 is formed. The inner peripheral surface of the mounting cylinder portion 34 is a communication port 34 a that allows the piston body 23 and the inside of the diaphragm 21 to communicate with each other, and the other end portion of the diaphragm 21 is fixed to the outside of the mounting cylinder portion 34. A metal wire 19b is embedded in the other end portion of the diaphragm 21, and the airtightness between the piston 20 and the diaphragm 21 is maintained and the end portion is reinforced.

  The piston body 23 and the lid member 24 are separately molded by resin, such as by injection molding. The piston body 23 and the lid member 24 are joined by abutting the abutting surface 32 of the piston body 23 and the abutting surface 35 of the lid member 24. Is done. As a result, it is possible to easily form the bottomed, narrow-mouthed container-shaped piston 20 and to reduce the weight and cost of the piston 20. In order to join the piston main body 23 and the lid member 24 with the respective abutting surfaces 32 and 35, the respective abutting surfaces 32 and 35 are abutted in a state of being heated and melted in advance by a heating device, whereby the piston main body. 23 and the lid member 24 can be welded. In FIG. 2, a joined portion, that is, a welded portion joined by such welding means is indicated by reference numeral 38.

  The cylindrical wall 27 is inclined radially outward from the outer peripheral portion of the closing wall 26 to the opening end 28 so that the piston body 23 can be easily injection-molded, and the draft angle of the inner peripheral surface of the cylindrical wall 27 is 0.5 ° to It is preferable to set in the range of 1.5 °, and the draft angle of the outer peripheral surface is preferably set in the range of 0.5 ° to 3.5 °.

  The rubber diaphragm 21 is internally provided with reinforcing cords (not shown) made of polyamide resin and the like arranged obliquely to prevent deformation and breakage of the diaphragm 21. A folded portion 21 a that covers the outside of the cylindrical wall 27 is formed at an intermediate portion between one end portion fixed to the curled portion 18 a of the diaphragm 21 and the other end portion fixed to the outer peripheral surface of the mounting cylindrical portion 34. The folded portion 21 a covers the joint portion 38 between the piston body 23 and the lid member 24, and deterioration of the joint portion 38 is suppressed by the diaphragm 21.

  An expansion / contraction chamber 36 is formed inside the diaphragm 21, and when the axle 12 moves up and down with respect to the vehicle body frame 10, the expansion / contraction chamber 36 expands and contracts due to the vertical movement of the piston 20. The expansion / contraction chamber 36 communicates with an air chamber 37 formed inside the piston 20 via a communication port 34 a so that no flow resistance is generated in the air flow between the expansion / contraction chamber 36 and the air chamber 37. Thus, the air chamber expands and contracts as a whole. Thus, by increasing the air capacity including the air chamber 37, the spring constant of the air spring 16 can be set low, and the characteristics of the air spring 16 can be improved.

  The air capacity for determining the spring constant of the air spring 16 is determined by the sum of the air chamber capacity S 1 of the air chamber 37 and the expansion / contraction chamber capacity S 2 of the expansion / contraction chamber 36. The air chamber capacity S1 of the air chamber 37 is set to be 40% or more with respect to the external volume of the piston 20, that is, the entire volume including the resin material portion forming the piston 20, and the sufficient air chamber capacity S1 is sufficient. It is secured. As a result, while the strength of the piston 20 is sufficient, more air can be used as the medium of the air spring 16, the spring constant of the air spring 16 can be set low, and a good riding comfort (vibration insulation) ) Can be obtained. Further, with respect to heat generated by repeated compression of the air spring 16, since the compressed air volume can be increased, the temperature rise can be suppressed.

  5A is a plan view of the piston, FIG. 5B is a bottom view of the piston, FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5, and FIG. It is line sectional drawing.

  As described above, the rib 31 is integrally formed in the piston main body 23 in a radial pattern, and the rib 31 is formed with an outer portion 31a in which the front end surface on the opening end 28 side of the piston main body 23 contacts the inner surface of the flange portion 33. The inner portion 31b has a tip end surface that is radially inward of the outer portion 31a and inclined toward the boss portion 25 via a step portion. The tip portions of the inner portion 31b and the boss portion 25 are Opposite to the communication port 34a, the thickness of the rib 31 is set to about 3 mm. As shown in FIGS. 4 and 7, twelve ribs 31 are provided at 30 ° intervals in the circumferential direction, but the number and thickness of the ribs 31 can be variously changed depending on the strength required for the piston 20 and the like. It is.

  As described above, the ribs 31 extending in the axial direction and the radial direction are integrally formed inside the piston main body 23 so that the piston 20 has a strength that the expansion / contraction chamber 36 can withstand even under a high pressure in a compressed state. Can do. Further, the air chamber 37 is formed between the adjacent ribs 31 without being completely partitioned by the ribs 31 by forming the upper part of the inner part 31b and the boss part 25 toward the communication port 34a. Each space is designed to communicate. As shown in FIG. 5 (B), the ribs 41 are formed radially on the outer surface of the blocking wall 26 as in the inside of the piston main body 23.

  As shown in FIGS. 3 and 7, columnar reinforcing protrusions 42 are integrally formed on the outer portions 31 a of the respective ribs 31, and these twelve reinforcing protrusions 42 are formed in the axial direction from the blocking wall 26. It extends and comes into contact with the inner surface of the flange portion 33 at a position corresponding to the lower side of the mounting cylinder portion 34. Reinforcing protrusions 42 project in a circular arc shape from both circumferential surfaces of rib 31 and are cylindrical, and ribs 31 are partially thickened by reinforcing protrusions 42 to increase the strength of piston 20.

  On the other hand, on the inner surface of the flange portion 33 of the lid member 24, as shown in FIGS. 4 and 7, twelve fitting projections 43 partially correspond to the respective reinforcing projections 42, and the tip portions of the ribs 31 are partially formed. And the reinforcing protrusion 42 are integrally formed. The fitting convex portion 43 protrudes from the inner surface of the flange portion 33 toward the inside of the piston main body 23, and the fitting convex portion 43 is a fitting concave portion in which the outer portion 31 a of the rib 31 and the distal end portion of the reinforcing protrusion 42 are fitted. 44 is formed, and the bottom surface of the fitting recess 44 is substantially flush with the inner surface of the flange portion 33. The reinforcing projection 42 and the tip of the outer portion 31a of the rib 31 are fitted into the fitting recess 44 in advance when the piston main body 23 and the lid member 24 are joined, and the piston main body 23 and the lid member 24 are positioned. Is called.

  As described above, the tip end portion of the rib 31 provided on the piston main body 23 is fitted into the fitting recess 44 of the lid member 24 so that the diaphragm 21 is damaged and the mounting cylinder portion 34 is damaged. Even if the connecting plate 18 abuts, the load received by the mounting cylinder portion 34 is applied to the rib 31 that is directly below. However, since the rib 31 is fixed in the fitted state, the rib 31 may not fall over. It is possible to prevent the entire lid member 24 from being damaged without being bent, and to increase the strength of the piston 20. In particular, since the reinforcing protrusions 42 projecting outward are provided on the surfaces of the respective ribs 31 and the tip portions of the reinforcing protrusions 42 are also fitted into the fitting recesses 44, the strength of the piston 20 can be further increased. . The fitting recess 44 and the reinforcing protrusion 42 and the tip end portion of the rib 31 entering the fitting recess 44 may be welded in the same manner as the joint portion 38, or may be bonded by an adhesive instead of welding. In this way, the strength of the piston 20 can be further increased by joining the piston body 23 to the lid member 24 by welding or an adhesive even at the portion of the reinforcing protrusion 42.

  FIG. 8A is an enlarged cross-sectional view taken along the line CC in FIG. 2, and FIGS. 8B to 8D are cross-sectional views showing the same parts as FIG. is there. The shape of the reinforcing protrusion 42 is not limited to the columnar shape protruding in an arc shape from the surface of the rib 31 as described above, but may be any shape as long as it protrudes from the rib 31 in the circumferential direction. 8B shows a prismatic reinforcing protrusion 42, FIG. 8C shows a U-shaped reinforcing protrusion 42, and FIG. 8D shows a T-shaped reinforcing protrusion 42. FIG. When the reinforcing protrusions 42 are formed in the shape of FIG. 8B to FIG. 8D, the fitting recesses 44 formed on the inner surface of the lid member 24 correspond to the cross-sectional shape of each reinforcing protrusion 42. It is formed into a shape.

  When the compressed air is supplied from the outside to the expansion / contraction chamber 36 and the air chamber 37 of the air spring 16 and incorporated in the air spring suspension 13, the folded portion of the diaphragm 21 as shown by the solid line in FIG. A portion of the length C 0 in 21 a overlaps the outer periphery of the cylindrical wall 27. When the vehicle travels, the air inside is compressed by the contraction of the expansion / contraction chamber 36, and the air spring 16 has a buffering action. Compressed air can be supplied and discharged from the outside to the expansion / contraction chamber 36, and the vehicle posture can be kept constant by supplying and discharging compressed air to the expansion / contraction chamber 36 in accordance with the load of cargo or the like to be loaded. . By ensuring a constant suspension stroke regardless of the load capacity, the spring constant can be set lower than a coil spring, but it is possible to prevent cargo damage and improve ride comfort. Become.

  FIGS. 9A to 9D are schematic views showing a joining process for joining the piston body and the lid member, and a method for joining the piston body 23 and the lid member 24 will be described with reference to FIG. .

  The piston body 23 and the lid member 24 are separately molded in advance using a resin material by injection molding or the like (preparation step). As shown in FIG. 9A, the piston body 23 manufactured in the preparation process is set on the fixing jig 51, and the lid member 24 is set on the fixing jig 52 (setting process). Here, the fixing jigs 51 and 52 are configured to grip the piston main body 23 and the lid member 24 by a gripping mechanism or the like (not shown) so that the respective center axes are not displaced.

  Under this state, as shown in FIG. 9A, an annular heating jig 53 is disposed between the opposed piston main body 23 and the lid member 24. Here, the heating jig 53 is provided with heating means (not shown) such as an electric resistance heater, for example, and the heating jig 53 causes the heating jig 53 to have a predetermined temperature (synthetic resin material). Melting temperature).

  Next, as shown in FIG. 9B from the state shown in FIG. 9A, the fixing jigs 51 and 52 are driven so as to be close to each other by a driving mechanism (not shown). By the proximity driving of the fixing jigs 51 and 52, the annular abutting surface 32 of the piston main body 23 and the abutting surface 35 of the outer peripheral portion of the end surface of the lid member 24 are brought into contact with the heating surface of the heating jig 53, respectively. The abutting surfaces 32 and 35 are melted (softened), respectively (connection part melting step).

  Thereafter, as shown by an arrow in FIG. 9C, the fixing jigs 51 and 52 are separated from each other by driving the driving mechanism. Then, after separating the piston body 23 and the lid member 24, the heating jig 53 is quickly moved in the horizontal direction by a drive mechanism (not shown), and the drive mechanism is continuously driven as indicated by an arrow in FIG. By doing so, the fixing jigs 51 and 52 are brought close to each other again. Then, the abutting surface 32 and the abutting surface 35 that have been melted or softened are butted against each other with a predetermined pressing force, and the piston body 23 and the lid member 24 are joined (melt joining step).

  At this time, since the tip portions of the rib 31 and the reinforcing protrusion 42 are fitted in the fitting convex portion 43, the piston body 23 is automatically positioned (centered) at a predetermined position with respect to the lid member 24. It has become. The piston main body 23 and the lid member 24 are connected only by the joint portion 38, and the rib 31 and the lid member 24 are not joined. This is because the air spring 16 receives an axial load between the vehicle body frame 10 and the support member 15 and is used in a compressed state, so that it is not always necessary to join the rib 31 and the lid member 24 together. . For this reason, for example, the air spring 16 can be easily disassembled after being removed, and the resin material is excellent in recyclability and the like. However, as described above, the tip of the rib 31 and the lid member 24 may be melted and heated by the same heating means.

  At this time, when the abutting surface 35 is provided so as to protrude toward the inner surface of the lid member 24, the amount of protrusion of the fitting recess 44 provided on the inner surface of the lid member 24 is larger than the amount of protrusion of the abutting surface 35. By making it equal or less, it is preferable because the movement at the time of fitting of the heating jig 52 and the piston main body 23 is hardly hindered.

  Next, the operation of the air spring 16 will be described with reference to FIG. In FIG. 2, the position of the turn-up portion 21a when the truck is traveling on a flat road with the load on the truck within the range of the appropriate load is indicated by a solid line. At this time, the folding portion 21 a has a contact range C 0 in contact with the outer peripheral surface of the cylindrical wall 27. Under such an extended state of the air spring 16, when the track passes through the uneven portion of the road surface, the air spring 16 is in a compressed state (bump) and an extended state (rebound).

  When the air spring 16 is compressed, for example, when a large truck rides on the convex portion of the road surface, the air in the expansion / contraction chamber 36 and the air chamber 37 is compressed, and the volume of the expansion / contraction chamber 36 decreases. Then, the folding | returning part 21a of the diaphragm 21 contacts in the contact range C1, for example, rolling on the outer surface of the cylinder wall 27 of the piston 20. FIG. At this time, the joint portion 38 between the piston body 23 and the lid member 24 is covered with the folded portion 21a of the diaphragm 21, and the joint portion 38 is in the contact range C1.

  Here, for example, the air spring 16 is further compressed as a large truck travels on a rough road such as an unpaved road with severe irregularities, and the pressure in the expansion / contraction chamber 36 and the air chamber 37 rises shockingly. Even in such a case, the joint portion 38 is covered and pressed by the folded-back portion 21a, so that the piston 20 can be protected from the high pressure acting in the direction of separating the joint portion 38.

  On the other hand, when the air spring 16 is extended, for example, when a large truck passes through a recess on the road surface, the air in the expansion / contraction chamber 36 and the air chamber 37 is expanded, and the volume thereof increases. Then, the folded portion 21a of the diaphragm 21 comes into contact with the outer surface of the cylindrical wall 27 of the piston main body 23 of the piston 20, for example, in the contact range C2. At this time, the joint portion 38 is covered with the folded portion 21a of the diaphragm 21 in the same manner as described above, and the joint portion 38 is in the contact range C2. As described above, the air spring 16 is compressed or expanded according to the unevenness of the road surface, and the shock absorber 17 shown in FIG. Propagation can be mitigated.

  As described above, in the air spring 16 described above, the resin-made piston 20 is formed by the bottomed cylindrical piston main body 23 and the lid member 24 joined thereto, so that the weight of the piston 20 is reduced. Can be achieved. Since the piston body 23 and the lid member 24 are integrated by the joint portion 38, the tip end portion of the rib 31 provided in the piston body 23 abuts on the bottom surface of the lid member 24 and fits in the fitting recess 44. The rigidity of the piston 20 can be increased. Thereby, the leakage of the compressed air from the expansion / contraction chamber 36 and the air chamber 37 to the outside can be reliably suppressed.

  Further, when the piston main body 23 is molded, the air chamber 37 having a large volume defined by the blocking wall 26 and the cylindrical wall 27 is formed in the piston main body 23 by performing die cutting from the opening end 28 side of the piston main body 23. Therefore, the post process for forming the air chamber 37 becomes unnecessary. Thereby, the manufacturing process of piston 20 can be simplified.

  Moreover, since the joint part 38 of the piston main body 23 and the cover member 24 is covered with the folded part 21a of the diaphragm 21, the air spring 16 described above can prevent the joint part 38 from being constantly exposed to the outside. . Therefore, the joint portion 38 is protected by the folded portion 21a, and deterioration of the joint portion 38 can be suppressed. Further, a plurality of ribs 31 extending radially between the inner surface of the cylindrical wall 27 and the boss portion 25 are provided, and the tips of the ribs 31 are fitted into the fitting recesses 44 of the lid member 24. The rigidity is increased, and as a result, the rigidity of the entire piston 20 can be increased.

  Further, when the lid member 24 is joined to the piston body 23, the lid member 24 is positioned at a predetermined position in the radial direction with respect to the piston body 23 by fitting the rib 31 into the fitting recess 44 of the lid member 24. Therefore, the lid member 24 can be automatically centered with respect to the piston main body 23, and the efficiency of the assembly work can be improved. Furthermore, since the piston main body 23 and the lid member 24 are fused and integrated in a state of being abutted on the respective abutting surfaces 32 and 35, the bonding strength between the lid member 24 and the piston main body 23 can be improved. . Further, since the piston main body 23 can be formed such that the air chamber capacity with respect to the outer volume of the piston 20 is 40% or more, a sufficient air chamber capacity can be obtained to reduce the spring constant of the air spring 16. it can.

  10 to 12 each show a modification of the piston 20 in the air spring of the present invention. In these drawings, the same members as those of the piston described above are denoted by the same reference numerals, and redundant description is omitted. .

  FIG. 10A is a perspective view showing an inner surface of a modified example of the lid member 24, and FIG. 10B is a perspective view showing a modified example of the piston body 23. As shown in FIG. 10, a protrusion 31 c that protrudes partially from the abutment surface 32 toward the lid member 24 is provided at the tip of the outer portion 31 a of the rib 31. A fitting recess 44 into which the protruding portion 31 c is fitted is formed on the inner surface of the lid member 24, and the fitting recess 44 extends from the inner surface of the lid member 24 toward the mounting cylinder portion 34. Thus, the strength of the piston 20 is increased by fitting the protruding portion 31 c of the rib 31 into the fitting recess 44 of the lid member 24. Also in this type of piston 20, if the protruding portion 31 c of the rib 31 is joined to the lid member 24 by welding or an adhesive, the strength of the piston 20 can be further increased. In the piston 20 shown in FIG. 10 as well, the reinforcing protrusion 42 may be provided on the rib 31, and in this case, the fitting recess 44 is formed in a shape in which the reinforcing protrusion 42 is fitted. In addition, you may make it provide the fitting convex part 43 in the cover member 24 similarly to the case where it shows in FIG.

  FIG. 11A is a cross-sectional view showing another modification of the lid member 24, and FIG. 11B is a cross-sectional view showing another modification of the piston body 23.

  A cylindrical portion 39 that protrudes toward the piston main body 23 is integrally provided on the outer peripheral portion of the lid member 24, and an end surface of the cylindrical portion 39 becomes an abutting surface 35 that abuts against the abutting surface 32 of the piston main body 23. ing. Thus, the lid member 24 of the piston 20 shown in FIG. 11 is provided with the mounting cylindrical portion 34 protruding upward in the drawing on the inner peripheral portion of the flange portion 33 and the cylindrical portion 39 protruding downward on the outer peripheral portion. It has been.

  On the other hand, the ribs 31 provided on the piston main body 23 protrude from the abutting surface 32 of the cylindrical wall 27 toward the lid member 24, and the fitting recess 44 into which the tip of each rib 31 is fitted is a lid. It is formed by a fitting convex portion 43 provided on the inner surface of the member 24. Further, the nut member 30 incorporated in the boss portion 25 has a truncated cone shape so that its outer diameter becomes smaller as it goes outward. Thereby, the fixing strength with respect to the boss | hub part 25 of the nut member 30 is raised, and the prevention (detachment | detachment) of the nut member 30 from the boss | hub part 25 is improved. Also in the piston 20 shown in FIG. 11, the joint portion 38 between the abutting surfaces 32 and 35 can be covered by the folded portion 21 a of the diaphragm 21 shown in FIG. 2, and deterioration of the joint portion 38 is suppressed.

  Also in the piston 20 shown in FIG. 11, the same effects as those described above can be achieved. In addition to this, since the outer peripheral portion of the lid member 24 has a cylindrical portion 39 extending toward the piston main body 23, a plurality of ribs 31 enter the cylindrical portion 39 and the respective distal end portions are fitted in the fitting recesses 44. Therefore, the rigidity of the lid member 24 in the radial direction with respect to the piston main body 23 can be increased.

  12A is a cross-sectional view showing still another modification of the lid member 24, and FIG. 12B is a cross-sectional view showing still another modification of the piston main body 23. As shown in FIG.

  The outer peripheral portion of the inner surface of the lid member 24 shown in FIG. 12A is the same surface as the bottom surface of the lid member 24, and the outer peripheral portion is an abutting surface 35. A portion corresponding to the communication port 34 a in the tip portion of the rib 31 protrudes from the abutting surface 32 so as to enter the communication port 34 a, and when the lid member 24 is joined to the piston main body 23, the projection 31 c Enters the inside of the mounting cylinder portion 34, and the centering of the lid member 24 with respect to the piston main body 23 can be easily performed at the time of joining. A portion of the tip end portion of the rib 31 that is radially outward from the protruding portion 31 c is fitted into a fitting recess 44 provided in the lid member 24. In this case, if the fitting concave portion extending in the axial direction is formed on the inner peripheral surface of the mounting cylinder portion 34 and the radial end portion of the protruding portion 31c is fitted into the fitting concave portion, the strength of the piston 20 is further increased. Can be increased.

  Also in this piston 20, since the joining part 38 which consists of each abutting surface 32 and 35 is coat | covered with the folding | turning part 21a of the diaphragm 21 shown in FIG. 2, degradation of the joining part 38 is suppressed. The nut member 30 shown in FIG. 12 has the same structure as the nut member 30 shown in FIG.

  Also in the piston 20 shown in FIG. 12, the same effect as that described above can be obtained. In addition to this, since the protruding portion 31c is allowed to enter the inside of the mounting tube portion 34, the strength of the piston 20 can be further increased.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the embodiment, the air spring is applied as a suspension spring for a truck. However, the air spring may be applied as a suspension device for a bus, a railway vehicle, and a construction machine. Further, the reinforcing protrusion 42 may be provided at a position radially outward from the rib 31 without being provided at a position corresponding to the mounting cylinder portion 34. Further, the air spring 16 may be turned upside down to attach the piston 20 to the vehicle body frame 10 and attach the connecting plate 18 to the support member 15.

It is the schematic which shows the air spring type suspension with which the truck was mounted | worn. It is sectional drawing of the air spring which is one embodiment of this invention. It is a perspective view which shows the piston main body of an air spring. It is a perspective view which shows the inner surface of the cover member fixed to a piston main body. (A) is a top view of a piston, (B) is a bottom view of a piston. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. (A) is a CC line expanded sectional view in Drawing 2, and (B)-(D) is a sectional view showing the same portion as (A) in the modification of a reinforcement projection. (A)-(D) are schematic which shows the joining process of a piston main body and a cover member. (A) is a perspective view which shows the inner surface of the modification of a cover member, (B) is a perspective view which shows the modification of a piston main body. (A) is sectional drawing which shows the other modification of a cover member, (B) is sectional drawing which shows the other modification of a piston main body. (A) is sectional drawing which shows the other modification of a cover member, (B) is sectional drawing which shows the other modification of a piston main body.

Explanation of symbols

10 Body frame (upper member)
12 Axle 13 Air spring suspension 15 Support member (lower member)
18 Connecting plate 20 Piston 21 Diaphragm (tubular elastic body)
21a Folding part 23 Piston main body 24 Lid member 25 Boss part 26 Closure wall 27 Cylinder wall 28 Open end 31 Rib 33 Flange part 34 Attachment cylinder part 34a Communication port 36 Expansion contraction chamber 37 Air chamber 42 Reinforcement projection 43 Fitting convex part (Fitting Joint)
44 Fitting recess (fitting part)

Claims (7)

An air spring that is mounted between the upper member and a lower member disposed below the upper member, and that relieves vibration propagated from the lower member to the upper member,
A resin-made piston main body having a closed wall provided with a boss portion attached to one of the upper member and the lower member, and a cylindrical wall extending in the axial direction from the closed wall, and having an open end at the tip; ,
A resin lid member that includes a mounting cylinder and is joined to the opening end of the piston main body to form a piston with an air chamber inside;
One end is fixed to a connecting plate that is attached to the other of the upper member and the lower member, while the other end is fixed to the attachment cylinder through a folded portion that covers the outside of the cylinder wall. A cylindrical elastic membrane that forms an expansion / contraction chamber communicating with the air chamber;
A plurality of ribs extending in the axial direction from the blocking wall toward the lid member and extending in the radial direction from the cylindrical wall toward the boss portion are integrally formed radially on the piston body, An air spring characterized in that a fitting portion is formed on an inner surface to be fitted to an end portion of the rib.   The air spring according to claim 1, wherein a reinforcing protrusion extending in the axial direction is provided on the rib.   The air spring according to claim 2, wherein the reinforcing protrusion is provided on a radially inner side of the rib.   4. The air spring according to claim 2, wherein the reinforcing protrusion is provided so as to correspond to the mounting tube portion. 5.   5. The air spring according to claim 2, wherein the lid member is provided with the fitting portion to be joined to the axial end portion of the reinforcing protrusion. 6.   The air spring according to any one of claims 1 to 5, wherein the fitting portion is provided on an inner surface of the lid member so as to protrude into the piston body.   The air spring according to any one of claims 1 to 6, wherein the fitting portion and the end of the rib are joined by welding.

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